Wells & Drainage cost guide

French Drain cost in Illinois

A french drain is priced by the linear foot, and the biggest single factor is whether it runs outside in the yard or inside along a basement footing. Interior drains cost far more because a crew has to cut and replace concrete. Length and add-ons like a sump connection or catch basins finish the estimate.

The direct answer · Illinois

A 100-foot exterior french drain in Illinois costs about $2,940, and typically runs $1,180–$4,110 depending on length, whether it is interior or exterior, and add-ons.

Model range

$1,180–$4,110

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$2,940

$1,180–$4,110 · Illinois

100 ft · Exterior (yard / curtain drain)

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Viewing:French Drain

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Top 6 selected states by modeled typical french drain cost.

Range Typical

				Confidence
FloridaFL	$910	$2,270	$3,180	measured
TexasTX	$920	$2,310	$3,230	measured
PennsylvaniaPA	$1,030	$2,570	$3,600	measured
New YorkNY	$1,120	$2,800	$3,920	measured
CaliforniaCA	$1,140	$2,850	$3,990	measured
IllinoisIL	$1,180	$2,940	$4,110	measured

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This a 100-foot exterior drain is shown for Illinois. Every row is priced by the same cost model that powers the calculator.

ComponentModeled rangeTypical

French drain, exterior (100 lin ft)mixed$1,180–$4,110$2,940

Total modeled range$1,180–$4,110

What changes the range

Cost drivers worth asking about.

Interior costs far more than exterior

An exterior yard drain is trenched in open ground, so it is the cheaper option. An interior perimeter drain requires cutting the basement slab, laying pipe against the footing, and pouring new concrete — that labor roughly doubles or triples the per-foot cost.

Length scales the whole job

Because pricing is per foot, a 200-foot run costs about twice a 100-foot run of the same type. Measure the wet area you actually need to protect rather than ringing the whole yard.

Sump and catch-basin add-ons

Interior drains usually discharge to a sump pump, which adds a basin and pump. Exterior systems may add catch basins at low spots. These are optional line items you can toggle.

Common questions

The practical details.

How much does a french drain cost in Illinois?

A 100-foot exterior french drain in Illinois costs about $2,940 ($1,180–$4,110). The same length run inside along a basement footing costs about $7,050 because of the concrete work.

What is the cost difference between an interior and an exterior french drain?

At 100 feet, an exterior drain averages about $2,940 while an interior drain averages about $7,050 — roughly $4,110 more — because interior work means cutting and re-pouring the slab.

How much is an interior french drain with a sump pump?

A full interior perimeter drain of about 140 feet with a sump connection runs around $11,670 ($7,930–$16,010) in Illinois, which matches typical wet-basement waterproofing quotes.

How much does a french drain cost per foot?

Exterior yard drains run on the lower end per foot; interior footing drains cost several times more per foot because of concrete cutting and replacement. Use the calculator to price your exact length.

Continue your research

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Water Well Drilling

Related guide

Sump Pump

National view

National french drain cost

How we estimate these costs: every number on this page is generated by our open cost model from published contractor pricing, then adjusted for state labor rates. Read the full methodology and data sources. Last reviewed 2026-08-15.